1. Field of the Invention
This invention relates to a farrowing pig pen.
Pig pens conventionally comprise an enclosure for the pig, defined by two generally parallel side walls, a back wall, and a front gate through which access can be gained to the pen. Such pens can be made from tubular elements, especially galvanised steel tubes. Pig pens are commonly adapted for use by sows when they are farrowing, to accommodate the sow and to allow her piglets access to be able to suckle.
A pig pen which is intended for use by a sow when farrowing can have one of the side walls, the back wall and the gate bearded up to retain the piglets in the pen. A retreat can be conveniently fitted to the other of the side walls, which might have a generally box-like form open along one side to allow the piglets access to the sow in the enclosure. A retreat in the form of a box is being often referred to as a "piglet creep". The retreat can be fitted with a source of heat for the piglets within it, for example in the form of heating lamps, which can attract the piglets into the retreat after they have finished feeding from the sow.
The pen is generally constructed so that movement of the sow within it is somewhat restricted in the enclosure, forwards and backwards as well as side to side, while allowing the sow to move between standing and lying positions. The piglets will suckle from the sow when she is in a lying position. The sow moves from a standing position to a lying position either by sliding against one side wall of the enclosure, or by collapsing her legs and rolling to a lying position. Whichever technique is used by the sow, there is a significant risk that one or more piglets will be trapped beneath the sow, and be crushed or smothered by her as she lies down. It has been found that there is a significant mortality rate among piglets as a result of accidents of this kind.
2. Brief Description of the Prior Art
In British Patent Publication No 2117620A there is disclosed one arrangement for overcoming this problem, an electro-optical sensor arrangement, such as an infra-red transmitter and receiver, is arranged such that on standing the sow breaks the light beam to initiate a blower which blows air beneath the sow to drive the piglets into the piglet creep and, on the the sow lying down, the light beam circuit is completed, and the blower is switched off. However, in practise, in the humid, dusty and frequently heavily contaminated environment the infra-red transmitter and/or receiver can be obscured, rendering the device inoperable with air continuously blowing, and such devices have never been popular.
Further, the arrangement proposed in GB Patent Application No 2117620 teaches operation of the arrangement only when the sow is standing. However, when the sensor is set to detect a sow in the standing position, said sensor will not detect a sow in a partially upright position, e.g. sitting on her haunches, and with the sow in a sitting position with the arrangement not actuated, to blow air under the sow, the piglets are in danger when the sow lowers to her lying position.